My objectives are to study various aspects of the recA-inducible systems of E. coli, B. subtilis and Pseudomonas aeruginosa and to detect analogous inducible systems in other bacteria. With respect to E. coli my aims are to mutationally dissect the recA protein by isolation of recA mutants having split phenotypes; to identify new genes involved in generation of the signal which activates recA; to measure in vitro binding of possible allosteric inhibitors to purified tif protein; to devise an in vitro assay for the cellular protein which mediates mutagenic repair; to insert Mu-lac phage into the mutagenesis gene of pKM101 so as to have an in vitro assay for the plasmid-coded repressor of mutagenesis; to study regulation of synthesis of both the pKM101 mutagenesis gene and the cellular umuC gene; to identify the inducible filamentation protein and to determine its intracellular location; to clone the mutated forms of genes sfiA and sfiB in order to isolate the gene products which suppress filamentation; to isolate new sfi mutations showing different proteolytic specifities; to identify new recA-inducible genes in E. coli, by inserting Mu-lac phage into the desired genes and detecting tif-mediated lac expression.